1. Field of the Invention
The invention relates to an image scanner, and more particularly, to an image scanner using one scanning pass to perform a preview scan and a formal scan.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a perspective view of a prior art image scanner 10. The image scanner 10 comprises a housing 12 having a transparent platform 14 for placing a document 16 to be scanned, a calibrating area 18 installed in the housing 12 at a front end of the transparent platform 14, and a scanning module 20 movably installed in the housing 12 for scanning the document 16 on the transparent platform 14, a driving device (not shown) for driving the scanning module 20, and a control circuit (not shown) for moving the scanning module 20 forward or backward. The calibrating area 18 comprises a white calibrating strip 24 and a black calibrating strip 26 for calibrating image signals generated by the scanning module 20.
When performing a preview scan, the control circuit first uses the driving device to drive the scanning module 20 to scan the calibrating area 18 at the front end of the housing 12. Then the scanning module 20 is moved backward to scan the document 16 positioned on the transparent platform 14. Finally, the scanning module 20 is moved forward to the front end of the housing 12. When the preview scan is performed, the control circuit stops moving the scanning module 20 and waits for a formal scan signal. When the control circuit receives a formal scanning signal, the control circuit again uses the driving device to drive the scanning module 20 to scan the calibrating area 18, and then drives the scanning module 20 backward to scan the document 16 on the transparent platform 14 to perform a formal scan. Finally, the scanning module 20 is moved forward to the front end of the housing 12.
Throughout this scanning process, time is wasted because the scanning module 20 has to make two scanning passes in the housing 12 to scan the document 16. Although a high speed scanning module can help alleviate this problem, it is very costly.
It is therefore a primary objective of the present invention to provide an image scanner using one scanning pass to perform a preview scan and a formal scan to solve the above mentioned problems.
Briefly, in a preferred embodiment, the present invention provides an image scanner comprising:
a housing having a transparent platform installed on it for placing a document;
a calibrating area installed in the housing at a front end of the transparent platform; and
a scanning module movably installed in the housing for scanning the document on the transparent platform;
wherein when performing a preview scan, the scanning module at a front end of the housing will move backward to scan the calibrating area to calibrate the scanning module and then scan the document on the transparent platform, and when performing a formal scan, the scanning module stopped at a rear end of the housing will move forward to scan the document and stop at the front end of the housing.
It is an advantage of the present invention that the scanning module using one scanning pass to perform a preview scan and a formal scan so the time for scanning is much reduced. It also obviates the need for an expensive high-speed scanning module.
These and other objects and the advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.